Functional antibodies are an important therapeutic option for treatment of a wide variety of diseases. Currently, the field of immunochemistry has turned its attention to more challenging goals such as the generation of broadly neutralizing antiviral antibodies where a useful molecule may be very rare. This frequency problem has been largely solved by the advent of combinatorial antibody libraries where today one can select from a repertoire that contains as many as 1011 different members. As an example, the power of this approach has been demonstrated in the study of influenza viruses where the selection of rare antibodies has led to the discovery of new modes of virus neutralization thereby offering previously unrealized possibilities for therapy and even the generation of a universal vaccine.
However, even with a solution to the frequency problem, isolation of an antibody whose function goes beyond simple binding is still a painstaking process. There is a need in the art for better means for identifying functional antibodies from pools of candidate molecules. The present invention is directed to this and other needs.